Mechanochemical route to high-purity halide perovskites with real-time temperature tracking

Mechanochemical synthesis is a sustainable and scalable approach for producing halide perovskites, offering key advantages over traditional solution-based methods, such as solvent-free processing, improved stoichiometric control, and reduced toxicity. In this work, we present a detailed study on the mechanochemical synthesis of MAPbI3 and MAPbBr3, with real-time monitoring of temperature inside the rotating jar to optimize the grinding conditions. We find that the temperature increase primarily originates from mechanical impact rather than the exothermicity of the reaction and does not limit perovskite formation and quality. Ultra-pure MAPbI3 is readily obtained in under 10 minutes, while MAPbBr3 requires longer grinding times for complete conversion (30 min). Prolonged milling yields finer powders, which are essential for formulating well-dispersed, DMF-free inks. These inks enable the fabrication of perovskite films via slot-die coating under ambient conditions. Our findings highlight that real-time thermal diagnostics provides a valuable tool for optimizing mechanochemical synthesis protocols and the importance of powder refinement to achieve homogeneous films suitable for scalable optoelectronic applications.